RNA
RNA RNA = RiboNucleic Acid Structural units = nucleotides Nucleotide – 3 part: A sugar – ribose A phosphate group A nitrogen base
RNA Nitrogen Bases – name source for the nucleotides A = adenine U = uracil C = cytosine G = guanine
RNA Types 3 types of RNA: Messenger RNA (mRNA) – carries genetic information from DNA in nucleus to ribosome; three base sequence called a codon Ribosomal RNA (rRNA)- makes up ribosomes, where protein is made Transfer RNA (tRNA)- transfers amino acids from the cytoplasm to the ribosome; its three base sequence is called an anitcodon
Differences between… DNA & RNA Deoxyribose Sugar 2 strands Thymine Remains in nucleus Ribose Sugar 1 strand Uracil Can leave nucelus
Transcription
Transcription DNA mRNA (occurs in the nucleus) a. The complementary strand of RNA is built by the enzyme RNA Polymerase RNA polymerase binds to & separates the DNA strands at promoter sites Promoter - 3 base sequence that serves as a starting and ending points for RNA to be made
Transcription RNA polymerase uses one strand of DNA as a template to make the complementary strand of mRNA
DNA contains… Introns – nucleotide sequences that do NOT code for proteins Exons – nucleotide sequences that do code for proteins
RNA polymerase copies both introns and exons, but before mRNA leaves the nucleus… Introns are cut out of the sequence Exons are spliced (glued) back together to form the final mRNA
mRNA travels to the ribosomes (outside of nucleus)